Pneumatic slide valves

ABSTRACT

A double-pilot pneumatic slide valve of the kind in which a slider is movable to-and-fro within a surrounding housing by air under pressure through one pilot port to move the slider in one direction and through a second pilot port to move the slider in an opposite direction, movement of the slider causing alterations between the connections between main airports in the housing is provided with a slider which is part-cylindrical and has a crosssectional shape which is a segment of a circle. The slider is movable axially on its flat face, which slides on a flat base surface of the housing, by the pilot air pressure acting directly on the end faces of the slider and two spaced-apart seals are formed between the part-cylindrical face of the slider and an adjacent face on the surrounding part of the housing by two partcircular sealing rings which are carried in grooves in the face of the housing and bear against the part-cylindrical face of the slider. An air inlet passage communicates with the clearance space enclosed between the slider and the housing in between the two part-circular seals so that when air under pressure is supplied to the valve this acts on the part-cylindrical surface of the slider in between the seals and urges the slider into contact with the flat base surface.

United States Patent [72] Inventor Thomas William Hamilton Primary E i er M Cary Nelson 27 Clevehurst Close Stoke g Assistant Examiner-Robert J. Miller Buckinghamshire, England Attorney-Holcombe, Wetherill & Brisebois [2i] Appl. No. 792,697 [22] Filed Jan. 21,1969 [45] P d M 16, 1971 ABSTRACT: A double-pilot pneumatic slide valve of thekind [32] Priority Mar. 11,1968 in which a slider is movable to-and-fro within a surrounding [33] Great Britain housing by air under pressure through one pilot port to move [31] 11741/68 the slider in one direction and through a second pilot port to move the slider in an opposite direction, movement of the slider causing alterations between the connections between main airports in the housing is provided with a slider which is [54] PNEUMATIC SLIDE VALVES part-cylindrical and has a cross-sectional shape which is a seg- 8 Chims, 7 Drawing Figs ment of a circle. The slider is movable axially on its flat face, which slides on a flat base surface of the housing, by the pilot [52] 1.5. CI 137/559, air pressure acting directly on the end faces of the slider and 137/625-66 two spaced-apart seals are formed between the part-cylindri- [51] Int. Cl ..Fl6k 37/00, cal face of the Slider and an adjacent face on the Surrounding F161 1 H06 part of the housing by two part-circular sealing rings which are [50] Field ofsearch 137/6256, carried in grooves i the face of the housing and bpar against the part-cylindrical face of the slider. An air inlet passage 559; 235/201 (ME); 251/176 communicates with the clearance space enclosed between the slider and the housin in between the two art-circular seals so [56] References Cited that when air under gressure is supplied 3, the valve this acts 7 UNITED STATES PATENTS on the part-cylindrical surface of the slider in between the 2,867,213 1/1959 Thomas, Jr. l37/559X seals and urges the slider into contact with the flat base sur- 3,349,800 10/1967 Herion et al. l37/625.66 face.

l6 |ZZ 46 a m 44 45 /2/J6 23 U 2; H l? vol 2 I \& -23 i/- $4 P f i 2/ a a /4 I I 459 J7 H J J/ I E 47 Patented March 16, 1971 3 Sheets-Sheet 1 A ltorneys I Inventor 37w. AMwTod uwi wuwbw Patented March 16,1971 3,570,533

3 Sheets-Sheet 2 Inbenlor IT w. HAM \LToH Allorneys Patented. March 116, 1971 3,570,533

3 Shee s-Sheet 5 J'dz's d h. M 47@@ W .5 26

lnven lor TW- HAMILTON K M M55 A llorney:

PNEUMATIC SLIDE VALVES This invention relates to double-pilot pneumatic slide valves in which a slider is movable to-and-fro within a surrounding housing by air under pressure supplied through one pilot port to move the slider in one direction and through a second pilot port to move the slider in an opposite direction, the movement of the slider causing alterations between the connections between main air ports in the housing.

In the most common previous form of such a valve, the slider is in the form of a block whichis pressed by spring pressure against a surface in the housing on which it slides and which contains the main ports between which the connections are made. The slider block is connected by means of integral push rods to pistons at each end and these pistons slide in cylinders with which the pilot ports communicate. To move the slider in one direction, air is admitted through one pilot port to act on one piston while the cylinder containing the other piston is vented and to move the slider in an opposite direction, air is admitted through the other pilot port to the other cylinder whilst the first cylinder is vented.

Such valves are used, amongst other purposes, in pneumatic logic systems and it is most important that the response time of the valve, that is the time taken for the slider to move from one end position to the other within the housing should be as short as possible. With the previous arrangement in which the slider block together with both the pistons have to be moved all at once, the inertia of the slider as a whole is very considerable and this is undesirable. The aim of the present invention is to provide a double-pilot pneumatic slide valve in which the inertia of the slider is reduced as far as possible so that the response time of the valve can also be reduced.

To this end, according to this invention, such a valve has a slider in the form of a block having a flat face and the slider is contained in a housing so that it is movable axially on its flat face, which slides on a flat base surface of the housing, by pilot air pressure acting directly on the end faces of the slider, a seal being formed between the face of the remainder of the periphery of the slider other than that of the flat face and an adjacent face on the surrounding part of the housing by a seal which is attached to one face and bears against the other face.

Preferably the slider is part-cylindrical and has a cross-sectional shape which is a segment of a circle, the seal being formed between the part-cylindrical face of the slider and the adjacent face of the housing by a seal which is part-circular and is carried in a groove in the one face.

By forming a seal between the slider and the housing in this way, the slider is enabled to act as its own piston with the pilot air pressure acting directly on it. The slider can be made of much smaller mass than was possible with the previous slider block with two pistons attached to it. By making the slider part-cylindrical, the sealing which then takes place against the part-cylindrical face is greatly facilitated.

The slider may have its fiat face held in engagement with the flat base surface of the housing toprovide a seal between these two surfaces by spring pressure as was previously done, but preferably there are two part-circular seals between the slider and the housing and these seals are spaced apart axially with an enclosed clearance space between the slider and the housing between them. The air inlet passage to the valve communicates with this space and thus the air under pressure supplied to the valve acts on the part-cylindrical surface of the slider and itself urges this into contact with the base surface of the housing.

Preferably the flat face of the slider lies along a diameter of its section so that the slider is semicylindrical. The seal or seals are then preferably each in the form of a half-circular resilient ring seal and each of these half rings is preferably carried in a semicircular groove in the inner face of the housing.

A part at least of the housing may be made of transparent material, for example perspex, and the pilot ports may then be provided with indicators which provide a visual indication of the application of air pressure to them.

An example of a valve constructed in accordance with the invention is illustrated in the accompanying drawings in which:

FIG. I is a longitudinal section through the valve along the Y axis of the slider;

FIG. 2 is a cross section as seen in the direction of the arrows on the line lIII in FIG. 1;

FIG. 3 is a plan of a base block of the housing on the line III-III in FIG. I and showing in chain-dotted lines the slider in one end position;

FIG. 4 is a plan similar to FIG. 3, but showing the slider in the other end position; I

FIG. 5 is a sectional plan on the line V-V in FIG. 1;

FIG. 6 is a plan on the line Vl-Vl in FIG. I; and

FIG. 7 is an underneath plan as seen in the direction of the arrow V11 in FIG. 1.

As shown in FIGS. 1 and 2 of the drawings, the valve has a housing formed by three blocks, namely an upper block I, a base block 2, and a bottom port block 3. The three blocks are fixed together by two bolts, which are not shown, but the heads of which bear against the upper block I and the shanks of which pass through clearance holes in the block I, further clearance holes 4 and 5, shown in FIGS. 3, 4 and 5 in the block 2, and into tapped holes 5 in the block 3.

The upper block 1 has a semicylindrical recess 6, which forms a valve chamber, and the bottom of which is closed by g the block 2. Within the recess 6 is a semicylindrical slider 7 which has an accurately flat bottom face which slides on the top face of the block 2 which is also accurately flat. The recess 6 is formed with semicircular rebates 8 and 9 at its two ends and these rebates are of slightly smaller radius than the recess 6 so that semicircular shoulders 10 and II are formed around the two ends of the recess 6.

The slider 7 has a radius which is slightly smaller than that of the recess 6, but greater than that of the two rebates I0 and 11. Thus when the slider 7 moves to the left-hand end of the recess 6 as seen in FIG. 1, it comes into contact with the shoulder 10 which locates it in one end position and when it is moved towards the right as seen in FIG. I it is located in a second end position by the shoulder 11.

The recess 6 has two semicircular grooves 12 in its curved surface and these grooves hold half-circular rubber O-rings 13 which form two seals between the semicircular faces of the recess 6 and of the slider 7.

One pilot airport at the left-hand end, as seen in FIG. I, of the recess 6 is formed by a bore I4 in the block 3, a bore 15 in the block 2, a blind bore I6 in the block I and a groove I7 extending between the rebate 8 and the blind bore I6. A second pilot airport is formed at the right-hand end of the recess 6 by similar bores 18, I9 and 20 and a groove 21.

The blind bore 16 holds a rubber telltale disc 22 and the blind bore 20 holds a similar disc 23. When air is admitted through the pilot port which starts at the bore I4, the pressure of the air presses the disc 22 upwards as the air flows through the groove 17 into the left-hand end of the recess 6. This moves the slider 7 into its right-hand end position in contact with the shoulder 11. Similarly the admission of air under pressure through the pilot port which starts at the bore 18 presses the rubber disc 23 upwards as air enters the right-hand end of the recess 6 through the groove 21 and this moves the slider 7 to its left-hand end position in contact with the shoulder 10. The spaces above the rubber discs 22 and 23 in the bores 16 and 20 communicate with the atmosphere through exhaust openings 24 and 25 respectively so that there is no back pressure preventing upward bulging of the discs 22 and 23. The block 1 is made of perspex so that the movements of the discs 22 and 23 can be observed and this gives an indication that the pilot air pressure is reaching the valve.

In addition to the bores 14 and I8 forming the pilot airports, the port block 3 is provided with a number of further bores forming the lower ends of a number of main air ports. Further, as shown in FIG. 6, these bores communicate with a corresponding number of grooves formed in the upper face of the block 3. Thus, a main air inlet bore 26 communicates with a groove 27; an exhaust bore 28 communicates with a groove 29; a first cylinder bore 30 communicates with a groove 31 and a second cylinder bore 32 communicates with a groove 33.

The grooves 27, 29, 31 and 33 in turn lead to further bores in the base block 2 as shown in FIG. 5. The groove 27 leads to a main air inlet bore 34; the groove 29 leads to an exhaust bore 35; the groove 31 leads to a first cylinder bore 36 and the groove 33 leads to a second cylinder bore 37. The bores 34 and 35 extend right the way through the block 2, but the bores 36 and 37 extend only about three-fourths of the way upwards through the block 2 and communicate at their upper ends with slots 38 and 39 respectively shown best in FIGS. 3 and 4.

FIGS. 3 and 4 are drawn to twice the scale of the remaining FIGS. of the drawings and they show the upper face of the block 2 with the main air ports grouped at its center and they also show in chain-dotted lines the flat face of the slider 7 which slides on the upper face of the block 2. As is shown in FIGS. 3 and 4, a series of grooves are formed in the fiat bottom face of the slider. These consist of axially extending grooves 40 and 41 near the two axially extending edges of the slider 7 and three transverse grooves 42, 43 and 44, which are slightly deeper than the grooves 40 and 41. In addition there is a bore 45 extending upwards through the slider 7 from the end of the groove 43 and opening at its upper end through the semicylindrical face of the slider 7 as shown most clearly in H0. 2.

In operation, the inlet bore 26 is connected to a supply of air under pressure, the exhaust bore 28 is open to atmosphere and the two cylinder bores 30 and 32 are connected to the two ends of the cylinder of a pneumatic ram or other pneumatically operated device which is to be controlled by the valve. The pilot bores 14 and 18 are also connected into a pneumatic system by which either one or the other of the bores is supplied with air under a pressure which may be much smaller than that of the pressure of the main air supply to the bore 26. When air is supplied to the pilot bore 18, the slider 7 is moved into its left-hand position as shown in FIG. 3. The air under pressure from the main supply issues from the bore 34 whence it passes upwards through the bore 45 into a space 46, shown in FIGS. 1 and 2, which lies in between the two O-rings 13 and is bounded by the circular surfaces of the recess 6 and the slider 7. This pressure acts on the slider 7 and holds its flat bottom face tightly in contact with the flat top face of the block 2. Both these faces are lapped flat to within two light bands so that there is no leakage between them.

The air under pressure also passes from the groove 40 to the groove 43 and thence through the slot 38 down to the bore 30 connected to one end of the cylinder of the pneumatic ram so that this end of the cylinder is pressurized. At the same time the other end of the cylinder of the pneumatic ram which is connected to the bore 32 is exhausted through the bore 35 because the slot 39 to which the bore 32 leads is connected to the bore 35 by the grooves 42 and 41. Thus with air under pressure supplied to one end of the cylinder of the pneumatic ram and the other end of the cylinder exhausted to atmosphere, the ram piston is moved in one direction.

When pilot air under pressure is supplied through the bore 14, the slider 7 is moved into its right-hand end position as shown in FIG. 4 and from this it will be seen that the first end of the cylinder of the pneumatic ram which communicates with the slot 38 is exhausted through the bore 35 via the grooves 44 and 41 and the other end of the cylinder of the pneumatic ram which communicates with the slot 39 is connected to the air supply bore 34 via the grooves 43 and 40. The bore 45 remains at all times in communication with the air supply bore 34 so that the supply 7 remains pressed against the block 2.

, The valve is intended to be fixed in position in a pneumatic logic or other control system by having the bottom of its bottom block 3 fixed to a base plate provided with ports which register with the bores 14, 18, 26, 28, 30 and 32. As the arrange ment of these bores is symmetrical, it is necessary to ensure that the valve is not fixed to the base plate the wrong way round as this would make all the connections between the ports and the bores incorrect and to ensure that the valve is correctly orientated, the block 3 has a projecting pin 47 which is placed offcenter and engages in a corresponding hole in the base plate of the system.

lclaim:

1. In a double-pilot pneumatic slide valve of the kind comprising a housing, a slider mounted for to and fro sliding movement within said housing, means in said housing defining a first pilot port and a second pilot port, means in said housing defining at least three main airports and connection means in said slider for providing interconnections between said main airports, whereby the supply of pressure through said first pilot port moves said slider in one direction to provide a first set of connections between said main airports and the supply of air under pressure through said second pilot port moves said slider in an opposite direction to provide a second set of connections between said main airports, the improvement wherein said slider consists of a block having a flat face with two axially extending edges and said housing includes means defining a fiat base surface within said housing, said slider being movable axially with its flat face sliding on said flat base surface by the supply of pilot air pressure through said first and second pilot ports, and said valve comprises sealing means which forms a seal extending from one axially extending edge of said flat face on saidslider to the other axially extending edge of said fiat face, between the remainder of the peripheral surface of said slider other than said flat face and an adjacent substantially parallel surface on a surrounding part of said housing, said sealing means being attached to one of said sub stantially parallel surfaces and bearing against the other of said substantially parallel surfaces, and said pilot air pressure acting directly on said end faces of said slider and on said sealing means.

2. A valve as claimed in claim 1, wherein said slider is partcylindrical, and further comprising means in said face to which said sealing means is attached defining a groove holding said sealing means and said sealing means forming a seal between the part-cylindrical face of said slider and the adjacent face of said housing.

3. A valve as claimed in claim 2, comprising two part-circular sealing means between said slider and said housing, said sealing means being spaced apart axially and defining, together with said slider and said housing an enclosed space, and means defining an air inlet passage through said housing communicating with said space whereby when air under pressure is supplied through said passage, said pressure acts on said part-cylindrical surface of said slider between said spaced apart sealing means and urges the fiat face of said slider into contact with said flat base surface.

4. A valve as claimed in claim 2, wherein said slider is semicylindrical with its flat face lying along a diameter of its section.

5. A valve as claimed in claim 2, wherein said sealing means consists of a half-circular resilient sealing ring and in which said housing includes means defining a semicircular groove in said adjacent face of the surrounding part of said housing, said ring being carried in said groove.

6. A valve as claimed in claim 2, wherein said means defining said pilot ports and said main airports in said housing are located below said flat base surface.

7. A valve as claimed in claim 2, further comprising transparent material forming at least part of said housing and including said means defining said pilot ports, and further comprising indicator means in said pilot ports, said means providing a visual indication of the application of air pressure to said pilot ports.

8. A valve as claimed in claim lin which all of said airports are formed in the flat base surface of said housing and the connection means in said slider are accessible only through openings in the flat face of said slider. 

1. In a double-pilot pneumatic slide valve of the kind comprising a housing, a slider mounted for to and fro sliding movement within said housing, means in said housing defining a first pilot port and a second pilot port, means in said housing defining at least three main airports and connection means in said slider for providing interconnections between said main airports, whereby the supply of pressure through said first pilot port moves said slider in one direction to provide a first set of connections between said main airports and the supply of air under pressure through said second pilot port moves said slider in an opposite direction to provide a second set of connections between said main airports, the improvement wherein said slider consists of a block having a flat face with two axially extending edges and said housing includes means defining a flat base surface within said housing, said slider being movable axially with its flat face sliding on said flat base surface by the supply of pilOt air pressure through said first and second pilot ports, and said valve comprises sealing means which forms a seal extending from one axially extending edge of said flat face on said slider to the other axially extending edge of said flat face, between the remainder of the peripheral surface of said slider other than said flat face and an adjacent substantially parallel surface on a surrounding part of said housing, said sealing means being attached to one of said substantially parallel surfaces and bearing against the other of said substantially parallel surfaces, and said pilot air pressure acting directly on said end faces of said slider and on said sealing means.
 2. A valve as claimed in claim 1, wherein said slider is part-cylindrical, and further comprising means in said face to which said sealing means is attached defining a groove holding said sealing means and said sealing means forming a seal between the part-cylindrical face of said slider and the adjacent face of said housing.
 3. A valve as claimed in claim 2, comprising two part-circular sealing means between said slider and said housing, said sealing means being spaced apart axially and defining, together with said slider and said housing an enclosed space, and means defining an air inlet passage through said housing communicating with said space whereby when air under pressure is supplied through said passage, said pressure acts on said part-cylindrical surface of said slider between said spaced apart sealing means and urges the flat face of said slider into contact with said flat base surface.
 4. A valve as claimed in claim 2, wherein said slider is semicylindrical with its flat face lying along a diameter of its section.
 5. A valve as claimed in claim 2, wherein said sealing means consists of a half-circular resilient sealing ring and in which said housing includes means defining a semicircular groove in said adjacent face of the surrounding part of said housing, said ring being carried in said groove.
 6. A valve as claimed in claim 2, wherein said means defining said pilot ports and said main airports in said housing are located below said flat base surface.
 7. A valve as claimed in claim 2, further comprising transparent material forming at least part of said housing and including said means defining said pilot ports, and further comprising indicator means in said pilot ports, said means providing a visual indication of the application of air pressure to said pilot ports.
 8. A valve as claimed in claim 1 in which all of said airports are formed in the flat base surface of said housing and the connection means in said slider are accessible only through openings in the flat face of said slider. 